The first Cupredoxin domain of Bilirubin oxidase (BOD), the bacterial endospore coat component CotA, and similar proteins
Bilirubin oxidase (BOD) catalyzes the oxidation of bilirubin to biliverdin and the four-electron reduction of molecular oxygen to water. CotA protein is an abundant component of the outer coat layer in bacterial endospore coat and it is required for spore resistance against hydrogen peroxide and UV light. Also included in this subfamily are phenoxazinone synthase (PHS), which catalyzes the oxidative coupling of substituted o-aminophenols to produce phenoxazinones. PHS has been shown to participate in diverse biological functions such as spore pigmentation and biosynthesis of the antibiotic grixazone. These are Laccase-like multicopper oxidases (MCOs) that are able to couple oxidation of substrates with reduction of dioxygen to water. MCOs are capable of oxidizing a vast range of substrates, varying from aromatic compounds to inorganic compounds such as metals. Although the members of this family have diverse functions, majority of them have three cupredoxin domain repeats. The copper ions are bound in several sites: Type 1, Type 2, and/or Type 3. The ensemble of types 2 and 3 copper is called a trinuclear cluster. MCOs oxidize their substrate by accepting electrons at a mononuclear copper center and transferring them to the active site trinuclear copper center. The cupredoxin domain 1 of 3-domain MCOs contains part the trinuclear copper binding site, which is located at the interface of domains 1 and 3.
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